The present invention relates to a method for manufacturing a group III–V compound semiconductor and a semiconductor device using the same.
In recent years, there is an increasing demand for a semiconductor laser element that outputs blue-violet light as a light source for a high-density optical disk of the next generation. Particularly, active researches and developments have been made for a light-emitting element made of a gallium nitride (GaN)-based group III–V compound semiconductor capable of operating in a relatively short wavelength range, i.e., a wavelength range of blue-violet light.
Since a gallium nitride-based semiconductor is chemically stable and has a high hardness, a wet etching method, which is used in a manufacturing process for other group III–V compound semiconductors such as gallium arsenide (GaAs) or indium phosphide (InP), cannot be used. Therefore, a dry etching method is usually used for etching a gallium nitride-based semiconductor.
However, a dry etching method, as compared with a wet etching method, is difficult to control so as to selectively etch a semiconductor layer to be etched or to stop etching at a desired thickness, for example.
For example, influences of the etching stop position in a semiconductor layer to be etched on the operating characteristics of a gallium nitride-based semiconductor laser element are reported in an article “Proc. of the 61st Meeting of the Japan Society of Applied Physics, Vol. 1, p.325 (7p-L-4), September 2000”. In this article, it is stated that it is necessary to accurately control the post-etching thickness of a p-type cladding layer provided on an active layer in order to reduce the operating current of a semiconductor laser element.
Another article “Proc. of the 47th Meeting of the Japan Society of Applied Physics and Related Societies, Vol. 1, p.378 (30a-YQ-7), March 2000” contains a report on a measurement of a real-time depth in dry etching for a nitride-based semiconductor laser element. However, the article fails to report on a method for controlling the etching on a semiconductor layer.
A conventional dry etching process for a nitride-based semiconductor is performed on a layered structure of a plurality of semiconductor layers having different mixed crystal compositions such as AlxGa1-xN (where 0. x. 1). Therefore, the etching rates for the respective semiconductor layers are measured in advance, and the process is performed while managing the etching time based on the measured etching rates.
However, with the conventional dry etching method for a group III–V compound semiconductor, it is necessary to measure and manage the etching rate for each of the semiconductor layers having different compositions. In addition, it is necessary to control and manage dry etching conditions such as the temperature and the plasma state, thereby decreasing the productivity and the yield and increasing the cost.